Among petroleum products, for example, lubricant, gas oil, and jet fuel are products in which importance is placed on cold flow property. Consequently, it is desirable that the base oil used for these products is such that its wax component, such as a normal paraffin or a slightly branched isoparaffin, which is a factor in deterioration of cold flow property, has been completely or partially removed, or converted into a component other than a wax component.
An example of a known dewaxing technique for removing the wax component from a hydrocarbon oil is a method in which the wax component is extracted using a solvent such as liquefied propane or MEK. However, this method suffers from the problem which is that not only are operational costs high, but the production yield decreases due to wax removal
As a method for improving the lubricant base oil yield, so-called isomerization and dewaxing techniques, which convert the wax component in a hydrocarbon oil into a non-wax component by a catalyst from the above-described solvent dewaxing method are widely known.
On the other hand, an example of a known dewaxing technique for converting the wax component in a hydrocarbon oil into a non-wax component is isomerization and dewaxing, in which the hydrocarbon oil is brought into contact with, in the presence of hydrogen, a bifunctional hydroisomerization catalyst capable of hydrogenation-dehydrogenation and isomerization, thereby isomerizing normal paraffins in the hydrocarbon oil to isoparaffins (e.g., Patent Literature 1).